A room measures 14 ft by 16 ft with 9 ft high walls. You must apply two coats of paint to the walls only. Deducting one 3 ft x 7 ft door and two 3 ft x 4 ft windows, and assuming coverage of 350 sq ft per gallon per coat, what is the MINIMUM whole number of gallons to buy?

Giải thích

Wall perimeter = (14 + 16) x 2 = 60 ft. Gross wall area = 60 x 9 = 540 sq ft. Openings = one door (3 x 7 = 21) plus two windows (2 x 3 x 4 = 24), total 45 sq ft. Net area = 495 sq ft. Two coats = 495 x 2 = 990 sq ft of coverage. 990 / 350 = 2.83 gallons, so round up to 3. Option a covers only one coat. Option d double-counts. Option c over-orders. Always base paint quantity on net area times number of coats, then round up.